A liquid crystal display panel with a transmissive liquid crystal display device includes the liquid crystal display device, and an illuminating device that is disposed behind the liquid crystal display panel so as to project light thereonto. A side (edge) light type illuminating device is known as this type of illuminating device, which includes a light guide plate that defines a clear plate made from an acrylate resin, and a light source that is disposed along one side or a plurality of sides of the light guide plate. The side light type illuminating device having this configuration has the advantage of being easily reduced in thickness compared with a direct illuminating device having a configuration that a light source is disposed behind a liquid crystal display panel.
Especially when the side light type illuminating device includes an LED (Light-Emitting Diode) as the light source, the light source has the advantages of a long life and a high luminous efficiency, which has been receiving widespread attention. FIGS. 16 and 17 are an exploded perspective view and a cross-sectional view of relevant components, respectively, which show a schematic configuration of a liquid crystal display device including a side light type illuminating device that includes LEDs as described above.
As shown in FIGS. 16 and 17, a liquid crystal display device 100 includes a liquid crystal display panel 103, an illuminating device (backlight device) 104, and other components.
A bezel 102 has a frame shape so as to cover a peripheral portion of the liquid crystal display panel 103. The bezel 102 is, together with a chassis 114, arranged to ensure strength of the entire liquid crystal display device 100. The liquid crystal display panel 103 consists of two glass substrates that are bonded together while sandwiching liquid crystals therebetween. The liquid crystal display panel 103 is arranged to display an image on its front face by using light emitted from the illuminating device 104.
The illuminating device 104 includes the chassis 114 having the shape of a box of low height. Optical sheets 107 to 109, a light guide plate 111, a reflection sheet 110, and an LED board 120 are housed inside of the illuminating device 104.
The light guide plate 111 includes a light entrance face 111a from which light emitted from LEDs 121 mounted on the LED board 120 enters, and a light exit face 111b from which the light that has entered from the light entrance face 111a is emitted upward (in a direction of light projection) as shown in FIG. 17. The light entrance face 111a defines a lateral end face of an end portion 111d of the light guide plate 111. The light exit face 111b defines a front face of the light guide plate 111.
The reflection sheet 110 is disposed so as to cover a back face 111c of the light guide plate 111, which is an opposite face to the light exit face 111b of the light guide plate 111. The optical sheets 107 to 109 include a diffusion sheet and a lens sheet, and are disposed so as to cover the light exit face 111b of the light guide plate 111.
A stack of the optical sheets 107 to 109, the light guide plate 111, and the reflection sheet 110 is disposed on a bottom plate 114a of the chassis 114 while fixed thereon by a frame 105 having a frame shape.
The plurality of LEDs 121 mounted on the LED board 120 are disposed close to the light entrance face 111a of the light guide plate 111. The plurality of LEDs 121 are spaced apart from each other at specified intervals along the light entrance face 111a such that light emitting surfaces 121a of the LEDs 121 oppose the light entrance face 111a of the light guide plate 111. In this case, the LED board 120 is attached to a light source holding member 115 disposed on the bottom plate 114a close to a side plate 114b of the chassis 114.
The light source holding member 115 has the shape of a so-called bracket (L-shaped mounting hardware), and is made by cutting aluminum. In this case, the light source holding member 115 consists of a long plate 115a to which the LED board 120 is attached, and a long plate 115b arranged to be fixed to the bottom plate 114a of the chassis 114 by fixation screws 116 that define fixation members such as flat head screws and hexagonal screws, the plate 115a and the plate 115b being disposed so as to have an L-shape. The following literature is cited as a prior art literature relating to the present invention.